In solar power generation apparatus and wind power generation apparatus, power conversion is performed by a power conversion apparatus before DC power or AC power generated by power generation means is supplied to an AC system.
In the power conversion apparatus, a pseudo AC waveform in PWM (Pulse Width Modulation) or the like is generated by an inverter circuit including a switching element such as an IGBT, and is then formed to be a sinusoidal waveform by a filter circuit including an inductor element such as a reactor and a capacitor element such as a capacitor.
In a large-capacity power conversion apparatus, iron cores of a reactor constituting a filter circuit are such that: laminated iron cores, each of which is formed by laminating a plurality of thin plates of magnetic material such as thin plates of silicon steel and amorphous, are used to reduce a loss (iron loss) during operation; and three coils of a U phase coil, a V phase coil, and a W phase coil are wound around three magnetic legs arranged on a plane.
In order to flow a magnetic flux generated in accordance with zero-phase impedance that is generated when a voltage and a current value of each phase and/or a mutual phase-difference in three-phase alternating current deviate from an ideal state, there is commonly used a three-phase five-leg type iron core in which two magnetic legs having no coil wound around are further added on both sides of three magnetic legs.
A structure of this three-phase five-leg type iron core is disclosed in, for example, PTL 1. PTL 1 discloses that a three-phase five-leg iron core is formed such that: four two-legged iron cores, each of which is a laminated iron core formed by laminating a plurality of thin steel plates, are arranged side by side; pairs of adjacent two legs constitute three main legs; and phase coils having respective phases are wound around the three main legs.